Creating Movies

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Revision as of 12:23, 7 November 2008 by AngelHerraez (talk | contribs) (another example of loop; also GIF file export; animGIF and AVI formats)
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An animation is just a sequence of images, so all one needs is Jmol to create a batch file of images. There is currently no menu option to do this, but a small bit of scripting can do the trick. It is possible to get the movie output from either one frame at several angles or from a series of frames.

Output Loop Script

The main part of the script is given here: based on a mail from Bob Hanson on the mailing list. If you want to rotate a single molecule, you need to uncomment the respective 'rotate' commands. If you want to loop over the timeframes in your coordinate file, you only need to change the 'nFrames' variable to the amount of frames you are currently using (this is given in the title of the main Jmol window). You might also want to change the width and height parameters to create a bigger or smaller animation.

name = "./frame0000.jpg";
nFrames = 125;
nDegrees = 1;
thisFrame = 0;
width = 640;
height = 480;

set zoomLarge false;

message loop;
thisFrame = thisFrame + 1;
fileName = name.replace("0000","" + ("0000" + thisFrame)[-4][0]);
#rotate x @nDegrees;  # use these options if you want to rotate the molecule
#rotate y @nDegrees;
#rotate z @nDegrees;
frame next; # only use this if you have a multiframe file.
write image @width @height @fileName;
if (thisFrame < nFrames);goto loop;endif;
background black;

Save this text in a file, for example 'movieloop.jmol'.

Alternative example

This uses the same principles, slightly different (though equivalent) code and is set for the rotation of the model in a single frame. In addition, it exports to gif format (only available in recent 11.7 versions) for later making an animated gif file outside Jmol:

load whatever_file.mol
color background [xD2DFEF]
  add any other rendering commands
for (var i=0; i<36; i=i+1)
  write image 200 200 @{"movie" + ("0000" + i)[-3][0] + ".gif"}
    /* 200 and 200 are width and height */
  rotate axisangle {1 1 0} 10
    /* axis is defined by X Y Z lengths between braces; this one is at 45 degrees
      and 10 (degrees) is angle of rotation, so the 36-loop gives a full turn
end for


Now you still need to create a viewstate for the initial display. To do this, load the system coordinates you are interested in, rotate and change background colors until the picture looks as you want it. This can be saved into a file with the command:

write state "moviestate.jmol"

A state file looks something like this (only some of the important parts are shown):

load "CoCr_125frames.XYZ";  # This part is essential!
cameraDepth = 3.0;
center {6.424099 3.137966 4.133584};
moveto /* time, axisAngle */ 0.0 { -704 -672 -228 173.73} /* zoom, translation */  62.1
2 0.0 0.06  /* center, rotationRadius */ {6.424099 3.137966 4.133584} 9.94055;;
slab 100;depth 0;

Creating a playable movie

  • Linux console:

To create the animation, make a file with first the viewstate and then the loop, for example by:

cat moviestate.jmol movieloop.jmol > movie.jmol

jmol movie.jmol
  • Jmol console (any OS):

Start Jmol, open the script console, and type:

script moviestate.jmol 
script movieloop.jmol 

Jmol will start, and show you the animation, while it is writing the output files.

Encoding to the mpeg format

The most straightforward way to encode to mpeg2 in Linux systems is "convert". This will create huge files and the needed mpeg2encode might not always be installed.

convert *.jpg movie.gif
convert *.jpg movie.mpg

Alternatively, encode to smaller mpeg4 files with mencoder, which comes along with mplayer.

mencoder "mf://*.jpg" -o movie.mpg -ovc lavc -fps 8

Many options and codecs are available, the default settings often create images that are too grainy due to the high image compression. Some testing by Mario Valle at CSCS gave optimal mencoder options for a movie of atomistic simulations. To have it run on default Windows installations (e.g. for use in Powerpoint), also use the msmpeg4v2 codec with autoaspect. The optimal combination of mencoder options then becomes:

mencoder "mf://*.jpg" -o movie.mpg -ovc lavc -lavcopts vcodec=msmpeg4v2:autoaspect:vbitrate=2160000:mbd=2:keyint=132:vqblur=1.0:cmp=2:subcmp=2:dia=2:mv0:last_pred=3 -fps 8

Fine tune the speed/length of the animation by varying the -fps (frames per second) option.

Encoding to animated gif format

You will need a third-party software for this. Load into it the full set of gif files generated by Jmol (gif format is only available in recent 11.7 versions of Jmol), choose the time step and the loop options and save into animated gif. These files will be viewable directly in any web browser.

Encoding to avi format

Some programas will be able to read multiple gif, png or jpg files and produce an avi video file. Be aware that the file size will likely be large; that's where the mpeg alternatives may be useful.